Abstract: A new series of bimetallic COMOC-2(V)/DUT-5(Al) frameworks are developed and fully characterized. Electron paramagnetic resonance and transmission electron microscopy confirm the homogeneous dispersion of Al/V in the entire framework. The study of the flexibility by means of CO2 pressure dependent XRD and high pressure sorption reveals the co-existence of two different large and a narrow pore phase in the entire pressure regime.

Abstract: We report on the structural alterations of the thermoelectric material CuCrS2 introduced by the removal of 1/3 of the Cu+ ions which are located between CrS2 layers. X-ray diffraction (XRD) and pair distribution function (PDF) analyses revealed a newly formed Cu0.66CrS2 phase with monoclinic symmetry and a 3a superstructure. Simultaneously, a distortion of CrS6 octahedra is observed strongly indicating the oxidation of Cr3+  Cr4+ leading to a Jahn-Teller distortion. The structural features extracted form XRD indicate a pronounced disorder in the cationic sub-lattice at moderate temperatures (400 K). Transmission electron microscopy (TEM) examination elucidates the formation of a second Cu0.66CrS2 phase without the superstructure, caused by incipient Cu+ mobility upon beam irradiation. The synergetic combination of high temperature XRD and TEM investigations unveiled the complete mechanism of the phase transition occurring at 503 K, where a transformation into the spinel CuCr2S4 and stoichiometric CuCrS2 occurs.

Abstract: Offsetting the impact of human activities on the biogeochemical cycle of mercury has become necessary for a sustainable planet. Herein, we report the development of a water-stable and eco-friendly metal–organic framework, which has the formula {Cu4
II[(S,S)-methox]2}.
5H2O (1), where methox is bis[(S)-methionine]oxalyl diamide. Its
features include narrow functional channels decorated with thioalkyl
chains, which are able to capture HgCl2 from aqueous media in an
efficient, selective, and rapid manner. The conscious design effort in terms of size, shape, and reactivity of the channels results in extremely efficient immobilization of HgCl2 guest species in a very stable
conformation, similar to that of the enzyme mercury reductase. Thus,
1 enables the highly efficient removal of toxic HgCl2 from aqueous media and reduces the [Hg2+] concentration from the dangerous level of 10 ppm to acceptable limits of below 2 ppb in drinking water. The unusual combination of a low-cost straightforward synthetic procedure
and high stability under environmental conditions, together with its ability to efficiently and rapidly remove poisonous mercury ions, places 1 among themost attractive adsorbents reported to date for the purification of contaminated water.

Abstract: Metal ions are frequently incorporated into crystalline materials to improve their electrochemical properties and to confer new physicochemical properties. Naturally-occurring phosphate apatite, which is formed geologically and in biomineralization processes, has extensive potential applications and is therefore an attractive functional material. In this study, we generate a novel building block for flexible optoelectronics using bio-inspired methods to deposit a layer of photoactive titanium-modified hydroxyapatite (TiHA) nanoparticles (NPs) on conductive polypyrrole(PPy)-coated wool yarns. The titanium concentration in the reaction solution was varied between 8-50 mol% with respect to the phosphorous, which led to titanate ions replacing phosphate in the hydroxyapatite lattice at levels up to 17 mol%. PPy was separately deposited on wool yarns by oxidative polymerization, using two dopants: (i) antraquinone-2-sulfonic acid to increase the conductivity of the PPy layer and (ii) pyroglutamic acid, to reduce the resistivity of the wool yarns and to promote the heterogeneous nucleation of the TiHA NPs. A specific titanium concentration (25 mol% wrt P) was used to endow the TiHA NPs on the PPy-coated fibers with a desirable band gap value of 3.68 eV, and a specific surface area of 146 m2/g. This is the first time that a thin film of a wide-band gap semiconductor has been deposited on natural fibers to create a fiber-based building block that can be used to manufacture flexible electronic devices.

Abstract: Cu2ZnSnS4 (CZTS) is a technologically important and complex quaternary semiconductor and a highly promising material for the absorber layer in sustainable thin film solar cells. Its photovoltaic performance is currently limited by low open-circuit voltage, thought to be due to a range of point defects such as disorder between the copper and zinc lattice sites. This is the highest-resolution neutron diffraction study reported for CZTS, which unambiguously identifies the crystal symmetry and accurately quantifies precise values for the disorder on all cation symmetry sites as a function of temperature. Two samples of CZTS were fabricated by solid state reaction and their compositions were measured by inductively-coupled plasma mass spectroscopy, which identified significant tin loss during growth, leaving the samples Sn-poor, Cu-rich and Sn-poor, Zn-rich respectively. Both samples were found exclusively to adopt the tetragonal kesterite crystal structure with significant cation disorder, which is investigated in detail over the range 4–1275 K. Importantly, and in contrast to previous reports, the 2a Wyckoff site shows disorder equal to or greater than the 2c site. The order–disorder phase transition was observed at different temperatures for the two compositions, 489 and 501 K respectively, lower than previously reported. The kesterite–sphalerite transition was observed between 1250 and 1275 K for the Sn-poor, Cu-rich sample, significantly higher than previously reported. These results provide new insights into the high levels of disorder present in CZTS and confirm that composition and cation disorder have a significant effect on the phase transition mechanism. This work will enable the development of routes to the fabrication of higher-efficiency photovoltaic devices.

Abstract: Here, we present a new microwave-solvothermal method for the preparation of iron oxide nanostructures using deep eutectic solvents as a more sustainable reaction medium. By varying the synthesis temperature and solvent water fraction, the methodology offers control over iron oxide phase, size, and morphology, using efficient, rapid (10 minute) microwave heating. Synthesis with pure DES gives small (<5 nm) superparamagnetic samples of γ-Fe2O3 or α-Fe2O3, whereas hydrated DES yielded either nanoshards or large rhombohedral nanoparticles without the superparamagnetic response. Nanostructures were solution-cast onto F[thin space (1/6-em)]:[thin space (1/6-em)]SnO2 films. The photoelectrochemical response of the prepared photoanodes was assessed, with a maximum measured photocurrent response of 0.7 mA cm−2 at 1.23 V vs. RHE. We measured the solvent structure using synchrotron WAXS, demonstrating the differences between the dry and hydrated solvent before and after heat-treatment, and showing that the hydrated solvent is remarkably resilient to extensive degradation.

Abstract: In contrast to monoiridium complexes, the study of diiridium complexes as dopants in phosphorescent organic light-emitting devices (PhOLEDs) is largely unexplored. We now describe the syntheses, detailed NMR analyses, X-ray crystal structures and optoelectronic properties of the new cyclometalated diiridium complexes 5 and 6 in which the iridium centres are bridged by oxamidato ligands. These complexes contain diastereomers – the meso form (ΔΛ) and the racemic form consisting of two enantiomers (ΔΔ and ΛΛ) – with anti-oxamidato bridges. The precursor μ-dichloro-bridged complex 4 is very weakly emissive in solution, whereas the oxamidato bridged complexes 5 and 6 are highly emissive (ΦPL 73% and 63%) with short excited state lifetimes of τP 0.84 and 1.16 μs, respectively. Cyclic voltammetry studies demonstrate that the oxamidato bridging ligand plays a role in mediating intramolecular interactions between the iridium centres. Density functional theory (DFT) calculations and time dependent-DFT (TD-DFT) calculations provide further insights into the structural, electronic, and photophysical properties of the complexes in their ground and excited states. Phosphorescent organic light-emitting diodes (PhOLEDs) using complexes 5 and 6 as the emissive dopants in a simple architecture using a solution-processed active layer give bright green electroluminescence with remarkably high luminance (Lmax > 25[thin space (1/6-em)]000 cd m−2) for diiridium complexes.

Abstract: Here we show that through a straightforward synthesis it is possible to create a bulk material, Na0.35MnO2, with isolated sheets. Due to such arrangement of the oxide layers, this ionic conductor was found to be genuinely pseudocapacitive, with charge storage not limited by diffusion of ions between stacked layers, resulting in capacitance values of 190 F g-1 under exceptionally high current rates of up to 200 A g-1.

Abstract: In the past 5 years, hybrid halide perovskites have emerged as a class of highly efficient photovoltaic (PV) absorbers, with excellent electronic properties and low cost synthesis routes. Unfortunately, despite much research effort, their long-term stability is poor and presents a major obstacle toward commercialisation. The layered perovskite (CH3NH3)2Pb(SCN)2I2 (MAPSI) has recently been identified as a promising PV candidate material due to its enhanced stability and favourable electronic properties. Here, we demonstrate, using relativistic hybrid density functional theory, that the MAPSI structural motif can be extended to include a range of other metals, halides and even pseudohalides. In this way, the electronic structure of MAPSI can be tuned without affecting its stability with respect towards decomposition. These results indicate the possibility of lead-free MAPSI analogues, with suitable properties for photovoltaic top cells in tandem devices.